Summary Retention in HIV care is associated with longer survival, viral suppression, and lower HIV transmission. HIV disproportionally affects men who have sex with men (MSM). In Peru, the HIV epidemic is concentrated among them (prevalence 12.2%), while only 0.4% of the general population is HIV+. Worryingly, MSM with HIV are less likely to stay engaged in care! than other population groups. Studies with MSM have reported efficacy of text-message (SMS) reminders for retesting of HIV and other sexually transmitted infections. However, more trials are needed with them in order to assess the use of SMS for increasing retention in HIV care in resource- limited settings, such as in Latin America. Two-way text messaging can provide an increased level of real-time support to patients. WelTel was the first randomized controlled trial using an interactive two-way text messaging approach that reported a significant increase in self-reported adherence and viral suppression. The hypothesis for this study is that an upgraded version of WelTel to deliver an interactive two-way SMS-based intervention will increase retention in care among HIV+ MSM in Peru. This career development award seeks: 1) to develop an SMS-based intervention to be delivered through the WelTel system to increase retention in HIV care among HIV-positive MSM at a government-based hospital in Peru; and 2) to determine the efficacy of the intervention for increasing retention in HIV care when compared with standard-of-care. I will recruit 208 HIV+ MSM and randomize them (1:1) to an intervention (receives the SMS-based intervention) and control (standard of care) group. I will follow them up throughout the duration of the twelve months course. The main outcome will be retention in HIV care within one year after enrollment. Results will be used to design a multi- site trial to assess the effectiveness of the intervention in improving retention in HIV care among HIV+ Peruvian MSM that will be submitted for R01 funding. A multi-disciplinary mentoring team will support me with expertise in areas related to my career plan: HIV prevention trials (Dr. Duerr), mobile health (Dr. Blas and Dr. Lester), HIV research (Dr. Gonzales), implementation science (Dr. Zunt), qualitative research (Dr. Galea), quantitative methods (Dr. Carcamo), and evaluation of interventions (Dr. Garcia). With them, I have designed a training plan to fill the gaps in knowledge and skills I need to succeed in my goals. I will obtain additional formal training in qualitative research and implementation science, and! statistical and epidemiological methods. I will also acquire skills in grant/manuscript writing and I will pursue continuous training in responsible conduct of research. This mentored research training support will enable me to achieve my goal of becoming a leading global health researcher at Universidad Peruana Cayetano Heredia, actively collaborating with top international institutions and fostering health policies with rigorous evidence.